curvature versus slope
  n = 527926 
  X=0, Y = 9.57 +/- 8.37 
  Weighted least-squares fit:  Y = 22.6 + 2.736 X  + -0.02657 X**2 

slope versus dZ, curvature < 5
  n = 188087 
  X=0, Y = 8.01 +/- 5.26 
  Weighted least-squares fit:  Y = 6.3 + 0.249 X  + 0.00213 X**2 
     at X = 100, Y = 52.5 
     effective RMSE xy = 81.9 

slope versus dZ, curvature < 15
  n = 289055 
  X=0, Y = 8.37 +/- 5.44 
  Weighted least-squares fit:  Y = 5.9 + 0.392 X  + 0.00062 X**2 

curvature versus dZ, slope < 10
  n = 216225 
  X=0, Y = 7.51 +/- 4.79 
  Weighted least-squares fit:  Y = 5.6 + 2.225 X  + -0.03710 X**2 


Number of samples 538669
Max dz = 900
Mean dz = 22
RMS dz = 41.0487515035
100cm = 95.8434585989 percentile value of dz